labview, DBL or (DBL)

labview >> DBL or (DBL)

by DavidT » Wed, 06 Jul 2005 15:40:33 GMT

Any control or indicator seen with [ ] is an array of they type. eg. [dbl] is an array of dbl's, [abc] is an array of strings, etc...
To create an array you can place an array control (From the Cluster and Array Palette) on the front panel and drag a control of the element type you want into the array. Or you can place an array constant (from the Array Palatte) on the block diagram and drag the element type into the array, then use the 'change to control option'.
Hope this helps.

While testing a test data cluster I load a random number for a DBL into a USR, save the cluster to disk, read back the data, and read the cluster and compare the two values. Due to the DBL's not being "equal" the test fails. Yet if I check my data visually the numbers are the same. I know this has been discussed before but no one seemed to have a good answer as to how you can eliminate the small errors LV creates when handling DBL's. Any suggestions?
Paul
7.1.1

I'm using the [DBL -> TimeStamp] conversion VI to modify the t0 property of a waveform. This technique was taken from NI-Scope Express.vi, and sets the relative display position of a plot on a waveform graph. <br><br>The problem is that this seems to be a one way conversion and it is not possible to recover the DBL value from the converted TimeStamp. Not only is there no available VI to perform the reverse [TimeStamp -> DBL] conversion, but no property of the TimeStamp shows that the value is changing (I used a probe with not only the value, but everything else available on the property nodes). I know the TimeStamp changes though, even when it always says zero, because when the DBL going in is changed, the position of the plot on the waveform graph shifts appropriately as the DBL value is changed.<br><br>After much wrangling, I've just realized I can add the t0 DBL as an extra waveform component to recover it later. This seems cumbersome though, duplicating information, and buggy that any number you convert into a timestamp is used appropriately, but cannot be recovered, and always says 0 when probed.